Apparatus for smoothing and compacting plastic layers



May 28, 1963 F. BUNGER ETAL APPARATUS FOR SMOOTHING AND COMPACTING PLASTIC LAYERS Filed March 7, 1956 United States atet APPARATUS The invention relates to an apparatus for smoothing and compacting surfaces of deformable plastic layers, more especially of layers of concrete flooring compound of all kinds.

As is known, the production of smooth, flat surfaces of large area from concrete, cement and like deformable materials, such as are today very often required, involved considerable difiiculty. The smoothing of such surfaces by hand is very difficult and in addition very costly. Efforts have therefore been made to carry out the work mechanically. One form of such an apparatus consists of a motor-driven, flat disc having a rounded edge, which is pushed over the surface to be treated by means of a control handle. The driving motor is disposed above the disc and is preferably elastically connected thereto, if desired through a gearing.

It is extremely difiicult to work with such a disc. The centre of gravity of the apparatus is fairly high, so that the disc can readily tilt over during operation and then roll on its periphery. This results not only in a completely uncontrollable deviation of the apparatus from the desired direction, but also unilateral penetration into the surface to be treated. Damage is thus inflicted on the surface, which it is difiicult to remedy. Therefore, such apparatus can only be operated by an experienced and wellapractisecl person, so that it is costly to use.

The present invention is intended to achieve the same object. The aforesaid difiiculties are avoided in the use thereof. Practical tests have shown that substantially better results are obtained if, instead of one disc, two or preferably three or more discs disposed in the same plane are employed. The discs are mounted in a common frame and are driven through gearing by a motor which is as far as possible centrally disposed above them. The provision of a plurality of discs has a double advantage. In the first place, a larger area is simultaneously treated, and in the second place the tilting which might occur with a single disc is substantially impossible with discs rotating independently of one another. With a large number of discs, this effect can be further heightened by rotation of the discs in different directions. This result may be achieved by associating with at least one of the discs, between the driving gear wheel and the driven gear wheels, an intermediate gear Wheel which is rotatably supported in the member bearing the discs. Such a multidisc apparatus can be guided and controlled without difiiculty even by unskilled persons, because the danger of the discs performing independent movement cannot arise. The guiding is consequently limited to the displacement of the weight of the apparatus. Moreover, by virtue of the larger bearing area the centre of gravity of the system is much more favourably situated than in the known apparatus. A further advantage resides in that each element of the surface can be successively treated a number of times in different directions with a multidisc machine, whereby the smoothness and the evenness of the surface are improved.

It is expedient to adapt the discs to be readily interchangeable so that they may be replaced by others when worn or as required. The whole apparatus may also be used for grinding solid surfaces, in which case the discs are replaced by grinding discs.

An electric motor is employed for the drive if power line current or a transportable generator is available. In other cases, a petrol engine will be employed for the drive.

If no special carriage is available for the transport of the machine, it is advantageous to provide a number of running wheels which are rendered inoperative during actual operation.

A constructional example of the apparatus according to the invention is diagrammatically illustrated in the drawings.

FIG. 1 is a side elevation of the apparataus of the invention and FIG. 2 is a plan view of the device of FIG. 1.

Mounted on the frame 1 is the driving unit 2. The three discs 4 are driven through the gear wheels 3. The gearing is enclosed in a protective housing 5. The control handle 6 serves to move the apparatus.

Secured in the corners of the frame, which is of triangular torm in the constructional example, are bearing brackets 7, in which wheel bearing members 9 are rotatably mounted on a horizontal pin 8. Mounted in the said wheel bearing members, so as to be rotatable about a perpendicular axis are wheel supports 10 in which wheels 11 are rotatably mounted. The wheel bearing members 9 are held in the illustrated position by springloaded locking members 12 and can be pivoted, for example through or into a further locking position (not shown) whereby the apparatus is brought out of its transport position into its operative position.

What We claim is:

1. In a power trowel adapted to compact and smooth a floor layer of deformable plastic material before setting, a horizontal frame member, a handle rigidly afixed to said frame member, a plurality of equal area trowel discs rotatably supported by said frame member and adapted to rotate in a common horizontal plane about parallel vertical axes, said discs adapted to float upon the surface of the deformable plastic material to be surfaced for support of said frame member, each disc supporting an equal portion of the power trowels weight, a motor centrally mounted upon said frame member and drive means interconnecting said motor and said discs for rotation of said discs upon energizing of said motor.

2. In a power trowel as in claim 1 wherein said frame member is of equilateral triangular configuration and three trowel discs are rotatably supported upon said frame member equidistant from the center of said frame member in triangular arrangement corresponding to the configuration thereof.

3. In a power trowel adapted to compact and smooth a floor layer of deformable plastic material before setting, a horizontal equilateral triangular frame member, a handle affixed to said frame member, three equal area trowel discs rotatably journaled to said frame member by vertical shafts for rotation in a common horizontal plane such that the vertical projection of each of. the sides of said frame member are substantially tangential to the .peripheries of a pair of discs, said discs adapted to float upon the surface of the deformable plastic material to be surfaced for support of said frame member, first gears mounted on each of said shafts, a motor mounted on said frame centrally located with respect to the axes ,of said discs, a second gear driven by said motor engaging each of said first gears for rotation of said gears upon energizing said motor and retractable Wheel structure attached to said frame member at the ver-tices thereof.

References Cited in the file of this patent UNITED STATES PATENTS 4 Roos July 26, Myers Sept. 26, Vinella May 8, Oelmann June 5, Engberg et al. May 26, Bickford Jan. 3, Steele Oct. 27, Johnson Oct. 23, Boulton Aug. 5, Fletcher Dec. 16, Bird Jan. 6, Atkin Jan. 13, Arones Apr. 13, Helbig Aug. 21,

FOREIGN PATENTS France Nov. 29, 

1. IN A POWER TROWEL ADAPTED TO COMPACT AND SMOOTH A FLOOR LAYER OF DEFORMABLE PLASTIC MATERIAL BEFORE SETTING, A HORIZONTAL FRAME MEMBER, A HANDLE RIGIDLY AFFIXED TO SAID FRAME MEMBER, A PLURALITY OF EQUAL AREA TROWEL DISCS ROTATABLY SUPPORTED BY SAID FRAME MEMBER AND ADAPTED TO ROTATE IN A COMMON HORIZONTAL PLANE ABOUT PARALLEL VERTICAL AXES, SAID DISCS ADAPTED TO FLOAT UPON THE SURFACE OF THE DEFORMABLE PLASTIC MATERIAL TO BE SURFACED FOR SUPPORT OF SAID FRAME MEMBER, EACH DISC SUPPORTING AN EQUAL PORTION OF THE POWER TROWEL''S WEIGHT, A MOTOR CENTRALLY MOUNTED UPON SAID FRAME MEMBER AND DRIVE MEANS INTERCONNECTING SAID MOTOR AND SAID DISCS FOR ROTATION OF SAID DISCS UPON ENERGIZING OF SAID MOTOR. 